の問題画像が

をダウンロードしながら、私は、リストの活動に画像をダウンロードしていた中のアプリを持っています。私はそれらをスレッドのキューに追加し、各イメージをathreadにロードしています。 softreferenceを使用してそれらを削除します。 iamが最初に画像をロードするときに、画像が読み込まれます。しかし、私はそれを下から上にスクロールすると、そのイメージのいくつかは再び読み込まれていません。進行状況バーはちょうど回転しています。あなたの誰かがこれで私を助けることができますか？の問題画像が

私は以下のURLで以下のコードと同じでした：

http://ballardhack.wordpress.com/2010/04/10/loading-images-over-http-on-a-separate-thread-on-android/

コード：

This line is there in itemlistadapter class. 

private ImageThreadLoader imageLoader = new ImageThreadLoader(); 

This block of code is present in getview() method in a listactivity. 

//Image downloading starts here 
try 
{ 
holder.progress.setVisibility(View.VISIBLE); 
Bitmap cachedImage = null;    


try 
{ 
cachedImage = imageLoader.loadImage(Item.ImageUrl, new ImageLoadedListener() 
{ 
public void imageLoaded(Bitmap imageBitmap) 
{ 
holder.imgitem.setImageBitmap(imageBitmap); 
notifyDataSetChanged();     
} 
}); 
System.out.println("Print the cache image" + cachedImage); 
} 
catch (MalformedURLException e) 
{ 
Log.e("itemlistadapter", "Bad remote image URL: " + Item.ImageUrl, e); 
} 
if(cachedImage != null) 
{ 
holder.imgitem.setImageBitmap(cachedImage); 
holder.imgitem.setVisibility(View.VISIBLE); 
holder.progress.setVisibility(View.GONE); 
} 
else 
{     
int idNoImage = R.drawable.giftsuggestionsnoimage; 
holder.imgitem.setBackgroundResource(idNoImage); 
} 
} 
catch(Exception e) 
{ 
System.out.println("Exception in Downloading image : " + e.getMessage());  
} 
return convertView; 
}

................ .................................................. ................................. ImageThreadLoaderClassのコードがあります：

import java.io.BufferedInputStream; 
import java.io.IOException; 
import java.io.InputStream; 
import java.lang.Thread.State; 
import java.lang.ref.SoftReference; 
import java.net.MalformedURLException; 
import java.net.URL; 
import java.net.URLConnection; 
import java.util.ArrayList; 
import java.util.HashMap; 
import android.graphics.Bitmap; 
import android.graphics.BitmapFactory; 
import android.os.Handler; 
import android.util.Log; 

/** 
* This is an object that can load images from a URL on a thread. 
* 
* @author Jeremy Wadsack 
*/ 
public class ImageThreadLoader { 
private static final String TAG = "ImageThreadLoader"; 

// Global cache of images. 
// Using SoftReference to allow garbage collector to clean cache if needed 
private final HashMap<String, SoftReference<Bitmap>> Cache; 
Cache = new HashMap<String,SoftReference<Bitmap>>(); 

private final class QueueItem { 
public URL url; 
public ImageLoadedListener listener; 
} 
private final ArrayList<QueueItem> Queue = new ArrayList<QueueItem>(); 

private final Handler handler = new Handler(); 
// Assumes that this is started from the main (UI) thread 

private Thread thread; 
private QueueRunner runner = new QueueRunner();; 

/** Creates a new instance of the ImageThreadLoader */ 
public ImageThreadLoader() { 
thread = new Thread(runner); 
} 

/** 
* Defines an interface for a callback that will handle 
* responses from the thread loader when an image is done 
* being loaded. 
*/ 

public interface ImageLoadedListener { 
public void imageLoaded(Bitmap imageBitmap); 
} 

/** 
* Provides a Runnable class to handle loading 
* the image from the URL and settings the 
* ImageView on the UI thread. 
*/ 

private class QueueRunner implements Runnable 
{ 
public void run() { 
synchronized(this) { 
while(Queue.size() > 0) { 
final QueueItem item = Queue.remove(0); 

// If in the cache, return that copy and be done 

if(Cache.containsKey(item.url.toString()) && Cache.get(item.url.toString()) != null) 
{ 
// Use a handler to get back onto the UI thread for the update 
handler.post(new Runnable() { 
public void run() { 
if(item.listener != null) { 
// NB: There's a potential race condition here where the cache item could get 
// garbage collected between when we post the runnable and it's executed. 
//Ideally we would re-run the network load or something. 

SoftReference<Bitmap> ref = Cache.get(item.url.toString()); 
if(ref != null) 
{ 
                    item.listener.imageLoaded(ref.get()); 
} 
} 
} 
}); 
} 
else 
{ 
try 
{ 
final Bitmap bmp = readBitmapFromNetwork(item.url); 
if(bmp != null) 
{ 
Cache.put(item.url.toString(), new SoftReference<Bitmap>(bmp)); 

//Use a handler to get back onto the UI thread for the update 

handler.post(new Runnable() { 
public void run() { 
if(item.listener != null) 
{ 
item.listener.imageLoaded(bmp); 

} 
} 
}); 
} 
} 
catch(Exception e) 
{System.out.println("Imagethreadloader:"+e.toString()); 
} 

} 

} 
} 
} 
} 
/** 
* Queues up a URI to load an image from for a given image view. 
* 
* @param uri The URI source of the image 
* @param callback The listener class to call when the image is loaded 
* @throws MalformedURLException If the provided uri cannot be parsed 
* @return A Bitmap image if the image is in the cache, else null. 
*/ 
public Bitmap loadImage(final String uri, final ImageLoadedListener listener)throws 
MalformedURLException  
{ 
// If it's in the cache, just get it and quit it 
if(Cache.containsKey(uri)) { 
SoftReference<Bitmap> ref = Cache.get(uri); 
if(ref != null) { 
return ref.get(); 
} 
} 
QueueItem item = new QueueItem(); 
item.url = new URL(uri); 
item.listener = listener; 
Queue.add(item); 

// start the thread if needed 
if(thread.getState() == State.NEW) { 
thread.start(); 
} 
else if(thread.getState() == State.TERMINATED) 
{ 
thread = new Thread(runner); 
thread.start(); 
} 
return null; 
} 

/** 
* Convenience method to retrieve a bitmap image from 
* a URL over the network. The built-in methods do 
* not seem to work, as they return a FileNotFound 
* exception. 
* 
* Note that this does not perform any threading -- 
* it blocks the call while retrieving the data. 
* 
* @param url The URL to read the bitmap from. 
* @return A Bitmap image or null if an error occurs. 
*/ 
public static Bitmap readBitmapFromNetwork(URL url) 
{ 
InputStream is = null; 
BufferedInputStream bis = null; 
Bitmap bmp = null; 
try { 
URLConnection conn = url.openConnection(); 
//conn.setUseCaches(true); 
conn.connect(); 
//Object response = conn.getContent(); 
//if (response instanceof Bitmap) { 
//bmp = (Bitmap)response; 
//} 
BitmapFactory.Options options = new BitmapFactory.Options(); 
options.inTempStorage = new byte[16*1024]; 
options.inSampleSize = 2; 
is = conn.getInputStream(); 
bis = new BufferedInputStream(is); 
try 
{ 
bmp = BitmapFactory.decodeStream(bis,null,options); 
}   
catch(Exception e) 
{ 
System.out.println("Imagethreadloader:"+e.toString()); 
} 
} 
catch (MalformedURLException e) 
{ 
Log.e(TAG, "Bad ad URL", e); 
} 
catch (IOException e) 
{ 
Log.e(TAG, "Could not get remote ad image", e); 
} 
finally 
{ 
try { 
if(is != null) 
is.close(); 
if(bis != null) 
bis.close(); 
} 
catch (IOException e) 
{ 
Log.w(TAG, "Error closing stream."); 
} 
} 
return bmp; 
} 
}

出典

2012-03-16 sravanthi V

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